The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.
Total hip replacement refers to a surgical procedure where a hip joint is replaced using a prosthetic implant. There are several different techniques that may be used, but all include a step of inserting an acetabular component into the acetabulum and positioning it correctly in three dimensions (along an X, Y, and Z axis).
In total hip replacement (THR) procedures there are advantages to patient outcome when the procedure is performed by a surgeon specializing in these procedures. Patients of surgeons who do not perform as many procedures can have increased risks of complications, particularly of complications arising from incorrect placement and positioning of the acetabular component.
The incorrect placement and positioning may arise even when the surgeon understood and intended the acetabular component to be inserted and positioned correctly. This is true because in some techniques, the tools for actually installing the acetabular component are crude and provide an imprecise, unpredictable coarse positioning outcome.
Some techniques may employ automated and/or computer-assisted navigation tools, for example, x-ray fluoroscopy or computer guidance systems. A computer assisted surgery technique may help the surgeon in determining the correct orientation and placement of the acetabular component. However, current technology provides that at some point the surgeon is required to employ a hammer/mallet to physically strike a pin or alignment rod. The amount of force applied and the location of the application of the force are variables that would not be controlled by these navigation tools. Thus even when the acetabular component is properly positioned and oriented, when actually impacting the acetabular component into place the actual location and orientation can differ from the intended optimum location and orientation. In some cases the tools used can be used to determine that there is, in fact, some difference in the location and/or orientation. However, once again the surgeon employs an impacting tool (e.g., the hammer/mallet) to strike the pin or alignment rod to attempt an adjustment. However the resulting location and orientation of the acetabular component after the adjustment may not be, in fact, the desired location and/or orientation. The more familiar that the surgeon is with the use and application of these adjustment tools can reduce the risk to a patient from a less preferred location or orientation. In some circumstances, quite large impacting forces are applied to the prosthesis by the mallet striking the rod; these forces make fine tuning difficult at best and there is risk of fracturing and/or shattering the acetabulum during these impacting steps.
Installation and assembly systems for a prosthesis that have employed a guidance system may typically require that the surgeon divert attention from the installation/assembly when accessing information from the navigation system to establish or check the installation/assembly.
For some navigation/guidance systems, each operating room could define a frame of reference with the navigation system calibrated into this frame of reference. Such a use makes it difficult to use the navigation system in a different operating room without first performing calibration procedures. Thus the navigation system imposes an additional cost on the surgeon and the facilities management in implementing these types of solutions.
Different intra-operative evaluation and alignment of a prosthesis, e.g., an acetabular cup during THR, may include use of an A-frame, Fluoroscopy, Computer navigation, and patient specific instrumentation (PSI). Use of devices such as this may allow a surgeon to determine a position/alignment of the prosthesis and provide a map, such as of the pelvis, allowing the surgeon to decide on how to align the prosthesis to the pelvis.
Two processes, considered separate and distinct, are implicated in the installation and positioning of a prosthesis: i) preparation of the installation location, e.g. the acetabulum for the acetabular cup in THR, and ii) insertion of the prosthesis. While many focus on ii) for determining accurate installation, both i) and ii) may be important as errors in alignment and directionality during site preparation, e.g., reaming, could adversely affect the final outcome and which may require more extensive processing in process ii) than may be the case when care is also taken during process i).
Some of the patent applications incorporated above address improvement over the use of a mallet impacting/striking an alignment pin to adjust an orientation of a mispositioned prosthesis.
What is needed is a system and method for improving upon prosthesis installation, such as including a real-time evaluation of tool and/or prosthesis alignment or position.